Research at the European XFEL: Femtosecond X-ray experiments research on gold complexes

Sharmistha Paul Dutta from European XFEL was probing the aurophilicity and solvation dynamics in stimuli-responsive dimer complexes at the FXE instrument (Femtosecond X-ray Experiments).
Optical studies suggest that in the "free" ligand configuration the aurophilic effect strongly depends on the solvent environment while the exact electronic and structural origins of aurophilicity remain unclear.
Combining pump-probe high energy resolution X-ray absorption spectroscopy (HERFD-XAS) and wide-angle X-ray scattering (WAXS) in solution, Dutta visualized the local redistribution of electron density as well as the drastic changes in molecular structure when a weak aurophilic bond is formed in the emissive triplet excited state. Since X-ray scattering is also sensitive to the nearest-neighbor solvation shell molecules, researchers will be able to monitor molecular rearrangements around the excited solute and thus reveal the critical role of the solvent environment.